1. Field of the Invention
The present invention relates to a fastener, and more particularly to a fastener for fastening a heat sink to an electronic device, whereby the heat sink can effectively dissipate heat generated by the electronic device.
2. Description of Related Art
It is well known that, during operation of a computer, electronic devices such as central processing units (CPUs) frequently generate large amounts of heat. The heat must be quickly removed from the electronic device to prevent it from becoming unstable or being damaged. Typically, a heat sink is attached to an outer surface of the electronic device to absorb heat generated by the electronic device. A fastener is needed to keep the heat sink in tight contact with the electronic device.
Referring to FIG. 5, a conventional fastener 10 for a heat sink 20 includes a head 12 and a shaft 14 extending integrally and downwardly from the head 12. The shaft 14 has threads machined onto an exterior thereof. The head 12 defines a cross-shaped groove (not shown) in a top end thereof for facilitating operation of a tool such as a screwdriver thereon. The shafts 14 of the four fasteners 10 extend through the heat sink 20 and then a printed circuit board 30 to threadedly engage with four thread holes 50 of a back plate 40. At this time, the heat sink 20 and an electronic device 60 mounted onto the printed circuit board 30 are fastened together so that the heat sink 20 can have an intimate contact with the electronic device 60. However, during use or transportation of the electronic device 60, the fasteners 10 are subject to vibration or shock whereby the threaded connection between fasteners 10 and the back plate 40 can be loose; when this happens, the heat sink 20 can no longer have an intimate contact with the electronic device 60.
What is needed, therefore, is a fastener for a heat sink which is capable of securely fastening the heat sink to an electronic device even when the electronic device is subject to vibration or other adverse circumstances.